Análise do efeito do tratamento térmico de têmpera e partição na resistência ao desgaste do aço-ferramenta AISI D6

Abstract

Cold-working tool steels, such as AISI D6, are used in industry in applications where excellent low-wear properties are required, such as knives and some types of dies and punches. In this context, the present work had as main objective to compare samples of AISI D6 steel submitted to the conventional quenching and tempering heat treatments, with the quenching and partition heat treatment. The output variables investigated were the resistance to friction wear, the resulting microstructure, microhardness and impact toughness (Charpy) of the treated samples. For this purpose, cylindrical specimens of 10 mm in diameter and 28 mm in height were made, which were heated in an oven at 900°C and subsequently followed the following cooling routes: (1) Quenching in oil with double tempering; (2) Quenching and partition at 100°C; and (3) Quenching and partitioning at 200°C. The Vickers microhardness tests were carried out with loads of 50 and 100 gf. For the microstructural characterization of the samples, a Scanning Electron Microscope equipped with a Backscattered Electron Diffraction detector (EBSD) was used. The wear test was performed on a pin-on-disk device with a load of 30 N and a speed of 0.6 m / s. In the wear tests, AISI 1020 steel diskshaped bodies with a diameter of 35 mm and a thickness of 7 mm were used. The results showed that the quenching and tempering treatment formed a microstructure of martensitic matrix with medium hardness equal to 530 HV, while the conditions of quenching and partition at 200°C and 100°C showed microstructure of martensitic / bainitic matrix with medium hardnesses of 720 HV and 640 HV, respectively. In addition, the condition of quenching and partitioning at 200 ° C was the one that showed the greatest resistance to wear followed by quenching and partitioning at 100°C and conventional quenching and tempering.